Nanotubes have one or more sheet-like matrices of carbon atoms configured into cylinders having one or more walls. Different types of nanotubes can have different properties. For example, nanotubes can be conductive, dielectric, or semiconductive. Nanotubes can accordingly be transistors, emitters, interconnects, or other components used in memory devices, displays, or other products. One challenge of using nanotubes is depositing the desired type of nanotubes onto a workpiece so that the nanotubes are in a desired configuration.
One process for depositing nanotubes onto a workpiece is to suspend the nanotubes in a solution, immerse the workpiece in the solution, and then remove the workpiece. After the workpiece is removed from the solution, the liquid evaporates and the nanotubes remain on the surface of the workpiece. The surface of the workpiece can have hydrophilic regions where the solution preferentially remains on the workpiece surface after removing the workpiece from the solution to deposit the nanotubes only on the hydrophilic regions. One drawback of this process is that the nanotubes are typically in a random configuration on the workpiece. Another problem with this process is that all the different types of nanotubes in the solution are typically deposited onto the surface of the workpiece. As such, this process may not provide the desired arrangement and/or types of nanotubes on a workpiece.
Chemical Vapor Deposition (CVD) processes similar to those used to deposit materials in the fabrication of semiconductor devices can be used to deposit nanotubes. CVD processes, however, also typically deposit the nanotubes in a random configuration. As such, one drawback of this process is that the nanotubes may not be arranged in the desired configuration on the workpiece.
Still another process for depositing nanotubes is to electroplate the nanotubes onto a workpiece. One such process immerses a workpiece in an electrolyte having a plurality of nanotubes and establishes an electrical field between the workpiece and a counter-electrode. The electrical field attaches the nanotubes to the workpiece such that the nanotubes are generally parallel to the direction of the electrical field. As a result, the nanotubes are typically parallel to each other and perpendicular to the workpiece. Although electroplating nanotubes onto workpieces can arrange the nanotubes in a desired configuration (e.g., parallel to each other), different types of nanotubes in a plating solution are generally plated onto the workpiece. As a result, undesired nanotubes may be deposited onto the workpiece along with desired nanotubes.